Various components of gas turbine engines, such as vanes and blades in a turbine section of the engine, are exposed to high temperatures and, in the case of rotating blades, may be subjected to strong mechanical loads during operation. Nickel-based superalloys may therefore be used as a preferred material for such components. The production of turbine blades and other components formed of such superalloys is complex and cost-intensive. Hence, there are efforts to produce as little scrap as possible, such as by repairing defects in production, and repairing damage resulting from service. For example, erosion, foreign object damage, and thermo mechanical fatigue cracks require repair to extend component life.
Gas turbine components, and in particular blades that are in operation, are routinely serviced and exchanged when necessary. In order to extend the operational life of the components, whenever possible they are refurbished, after which they may be used once again in a gas turbine. Such refurbishment may, for example, involve the necessity for build-up welding in damaged regions, in order to restore the original component features and/or dimensions. In particular, for superalloy components, a laser cladding operation may typically be utilized to perform the repair. Laser cladding may be performed with a relatively low heat input to apply metal depositions to a substrate, and avoids altering the material properties of the underlying superalloy component. Superalloy components typically comprise a single crystal and directionally solidified structure susceptible to recrystallization when subjected to a high heat input, such as may occur using conventional welding processes, such as plasma arc welding, or gas tungsten arc welding.
At present, there are ongoing challenges in the weld repair process. Various factors affect the quality of the build-up weld as the build-up weld is formed, including factors that may cause recrystallization within the weld material and factors that may cause microscopic separations or cracks in the weld material.